legacy boards officially deprecated

The x230-hotp-legacy, x230-legacy-flash, and x230-legacy boards are
officially deprecated.  They have been moved to the unmaintained_boards
directory.

CircleCI has been updated to reflect this change.

Signed-off-by: Thierry Laurion <[email protected]>

Author: tlaurion

.circleci/config.yml

@@ -293,27 +293,6 @@ workflows:
           requires:
             - x230-hotp-maximized
 
-      - build:
-          name: x230-legacy-flash
-          target: x230-legacy-flash
-          subcommand: ""
-          requires:
-            - x230-hotp-maximized
-
-      - build:
-          name: x230-legacy
-          target: x230-legacy
-          subcommand: ""
-          requires:
-            - x230-hotp-maximized
-
-      - build:
-          name: x230-hotp-legacy
-          target: x230-hotp-legacy
-          subcommand: ""
-          requires:
-            - x230-hotp-maximized
-
       - build:
           name: x230-hotp-maximized_usb-kb
           target: x230-hotp-maximized_usb-kb